1. Field of the Invention
This invention relates generally to an apparatus and a method for processing webs, and more specifically to an enclosed conduit, such as a tube, and a method for processing a continuous web or webs of varying length with a liquid solution.
2. Description of the Prior Art
U.S. Pat. No. 3,186,326 discloses a photographic film processing device having a plurality of tanks, each containing a different film processing solution, such as a developing solution, a stop solution, a fix solution, and a wash solution. In each tank, liquid bearings are provided at the top and bottom thereof immersed in the film processing solution. The film strip to be processed is guided over these bearings in a generally sinuous path forming one or more loops in each tank in which the major length of film is unsupported. U.S. Pat. No. 3,662,665 discloses a drum processing device having a peripheral, helical channel for guiding a film through successive solution baths. The film, however, is not supported on a liquid or solution bearing. U.S. Pat. No. 3,481,046 discloses a drum drying device in which a web is helically wrapped around a perforated drum through which air is directed for supporting the web on an air cushion while drying the web. One disadvantage of the prior art solution processing devices is that considerable force is required to transport the web through the processing device. Another disadvantage of such prior art devices is that the solution agitation achieved thereby, and which is of great importance in a photographic processing device, is not always uniform or consistent for the entire film area at any transport speed, and is normally at a low level of agitation. In the U.S. Pat. No. 3,186,326, the agitation is greater directly over the solution film bearing surface where the solution is forced against the film and less at the unsupported film-solution surface between the bearings. Accordingly, high agitation is achieved only part of the time, and is not consistent for the entire film area. In U.S. Pat. No. 3,662,665, the agitation is of a low level resulting from passage of the film through the solution baths and is virtually nonexistent in the remainder of the film path outside of the solution baths. U.S. Pat. No. 3,481,046 relates to a web dryer in which jets of drying air are used, and hence does not contemplate web processing by liquid solutions. Due to the spacing of the openings, if a liquid solution were used, the agitation resulting from the spaced jets of solution would undoubtedly be non-uniform, being greatest where the jet strikes the web, and least on the web surface between the jet impact points.
There is a need in the prior art for the constant and continuous displacement of a liquid solution in engagement with the film with substantially fresh or active liquid solution along the entire length of the solution engaged film surface. Such continuous liquid solution displacement provides uniform and consistent high solution agitation and uniform reproducible processing results at low as well as high film transport speeds.
There is a further need in the prior art for a photographic processing apparatus in which no moving parts are provided in the processing section other than liquid solution recirculating pumps.